Research: Physical Activity, Obesity and Health

The Journal of the American Medical Association reported that obesity has doubled among children and quadrupled among adolescents over the past 30 years, and more than one-third of children or adolescents in 2012 were overweight or obese (Ogden et al., 2014). These children are at an increased risk for developing health problems such as heart disease, diabetes, cancer, and hypertension as adults. The Centers for Disease Control and Prevention reported that overweight and obesity are leading cancer risk factors, and that 40 percent of all cancers diagnosed are associated with overweight and obesity (2017).

According to the 2012 National Health and Nutrition Survey, only one-quarter of youth ages 12-15 engage in at least 60 minutes of moderate-to-vigorous physical activity each day, as recommended by the Physical Activity Guidelines for Americans (Fakhouri et al., 2014). Among children, regular physical activity has been strongly associated with improved cardiorespiratory and muscular fitness and metabolic health, better bone health, and weight maintenance and energy balance, with greater benefits for participating in physical activity more often, longer, or at higher intensity (Duncan et al., 2016; Ward et al., 2015; US DHHS, 2008). Only half of American adults achieve recommended levels of physical activity (Ussery et al., 2017). There is a gender gap in physical activity levels, whereby women and girls are less likely than men and boys to attain recommended physical activity levels (Althoff et al., 2017; Ward et al., 2015).

Activity levels for many children have declined, due in part to a built environment that is unsafe for walking and bicycling, reduced physical education in school, and increased popularity of sedentary leisure-time activities. Safe Routes to School can create environmental, policy, and behavioral changes that increase physical activity and promote the health of both children and adults.  Articles summarized in this section address the overall health benefits of physical activity, specifically walking to and from school, as well as the impact that increased physical activity opportunities have on current obesity and health trends in the US.

Research Highlights:

  • Research demonstrates that children who walk or bicycle to school have higher daily levels of physical activity, lower body mass index and waist circumference, and better cardiovascular fitness than do children who do not actively commute to school (Mendoza et al., 2011; Davison, et al., 2008; Østergaard et al., 2012).
  • Two small lifestyle changes – a small increase in physical activity (walking an additional 2000 steps/day) and a small change in diet (eliminating 100 kcal/day) – help address childhood obesity by preventing excess weight gain (Hill, et al., 2007).
  • One study suggests that a 5% increase in neighborhood walkability is associated with 32.1% more minutes devoted to physically active travel and about one-quarter point lower BMI (0.228) (Frank, et al., 2006).
  • Children who walk to school get three times as much moderate to vigorous physical activity during their walk to school than during recess (Cooper et al., 2010). Children walk more when they live on more walkable routes with more open green space and less exposure to road traffic (Gallimore et al., 2011; Rahman, et al., 2011; Lamber et al., 2009).
  • Implementation of Safe Routes to School initiatives like Walking School Buses have demonstrated improved rates of walking to school, increased daily moderate-to-vigorous physical activity, and decreased overweight and obesity (Quarles, 2012; Mendoza et al., 2011; Mori et al., 2012; Kong et al., 2010).
  • Living in a walkable community has been associated with reduced prevalence of adolescent overweight and obesity (Slater et al., 2013).
  • Perceptions of safety and attractiveness impact a neighborhood’s walkability (Project for Public Space, 2016; Ussery et al., 2017).  
  • There are gender, racial, and class disparities in how much people walk. Compared to affluent and mostly white neighborhoods, neighborhoods with residents of low socioeconomic status and minority backgrounds are perceived as less attractive and safe because of crime (Ussery et al., 2017).   
  • Investing in bike lanes is an investment in public health: People bike more when the built environment supports bicycling by including bike lanes, bike racks, and traffic calming (Dill et al., 2013; Hipp et al., 2013; Winters et al., 2016).
  • In addition to more bike infrastructure and road engineering improvements to make bicycling safer, bicycle education is important (Pion et al., 2016).
  • US metro areas with greater multi-modal transportation options (i.e., walking, bicycling, public transit) have better public health outcomes: People make healthier lifestyle choices, have more quality leisure time, exercise more, have lower obesity rates, and live longer (Meehan et al., 2017; Frederick et al., 2017).
Multiple Short Bouts of Exercise Over 12-H Period Reduce Glucose Excursions more than an Energy-Matched Single Bout of Exercise
  • Objective: Long, uninterrupted bouts of sedentary behavior are thought to negatively influence postprandial glucose and insulin concentrations. We examined the effects of a 1-h bout of morning exercise versus intermittent walking bouts of short duration on glucose excursions and insulin secretion over 12-h.
Peer Influence and Physical Activity Behavior in Young Children
An Experimental Study

BACKGROUND: There is evidence that the presence of a friend increases physical activity behavior in school-aged children (≥ 8 years old) and in young adolescents. Little is known about the developmental trajectory of the effects of peer influences on children's physical activity.

Correlates of Urban Children's Leisure-Time Physical Activity and Sedentary Behaviors During School Days

OBJECTIVES:  Understanding correlates of physical activity and sedentary behaviors may contribute to fostering active lifestyles. This study aimed to identify correlates of physical activity and sedentary behaviors in leisure-time among Portuguese urban children, during school days.

Prevalence of Childhood and Adult Obesity in the United States

More than one-third of adults and 17% of youth in the United States are obese, although the prevalence remained stable between 2003-2004 and 2009-2010.

Health Implications of Transport Planning, Development, and Operations

This paper is an overview of impacts of transport on health for transport researchers and practitioners not familiar with them.

Joint Use of Public Schools: A Framework for a New Social Contract

There is a growing conversation about and demand for joint use as a way to provide services to children and families in convenient locations, improve opportunities for physical activity by increasing use of school recreational and outdoor spaces, leverage capital investments, and more. 

The Built Environment and Actual Causes of Death
Promoting an Ecological Approach to Planning and Public Health


Changes to the built environment can be an upstream intervention opportunity for determinants of high-priority health challenges like childhood obesity and should be an important consideration for planners.

America's Poor Neighborhoods Plagued by Pedestrian Death


Pedestrian fatalities are disproportionately higher in neighborhoods with lower incomes.

Socioeconomic Disparities in Elementary School Practices and Children's Physical Activity During School


  • Physical activity practices at schools may differ by school socioeconomic status.
Characteristics of Walkable Built Environments and BMI Z-Scores in Children
Evidence from a Large Electronic Health Record Database


Walkable built environment characteristics were associated with lower BMI z-scores (i.e., BMI compared to normal growth curves) among children.